FOREST RESEARCH NOTES
U.S.DEPARTMENT OF AGRICULTURE
FOREST SERVICE
CALIFORNIA FOREST AND RANGE
EXPERIMENT STATION "'
STEPHEN N. WYCKOFF,
Director
No. 81
February 14 1 19S2
SLASH DISPOSAL AND SITE PREPARATION IN CONVERTING
OIJ).;..·GROWTH SUGAR PINE-FlR FORESTS TO REGULATED· ST~
Donald T. Gordon and Richard D. Cosens
Division of Forest Management Research
Records of permanent sample plotsY and extensive observations
by fore~t m~nag~ment :esea:ch·work~1s indicate that tree selecti~n methods
of cutt1ng 1n sugar p1ne-f1r types::! have not favored the establlshment
of sugar pine reproduction. Since sugar pine is a highly prized lumberproducing species in the California region, special measures to preserv-e
or increase its place in the stand were made part of an experimental
logging project on the Stanislaus Experimental Forest in 1948 and 1949.
This projectwas a combination field test and demonstration of unit area
control,· a silvioultural sy~tem • .fpr keeping the ground stocked with trees
and producing at f'ull capaci;by~!/ This paper desotibes the slash-dhposal
a'nd site-preparation measures which are essential steps in est-ablishing
reg-eneration on chosen unit areas within the forest.
iJ
This proJect was under the direction of J)uncan Dunning, fo·rmer
Chief of the Division of Forest Management Research, and William E~
Hallin~ in charge of Silvicultural Investigations.
.
·Y
Fowells, H. A., and G., H. Schubert. 1951. Natural reproduotion
in certain cutover pine-fir stands of California. Jour. Forestry 49(3):
192~196~
. .
·Y
Sugar pine··fir type refers to. mixed stands of sugar pine, Pinus
lambertiana Dougl.; white fir, ·Abies c·orioolor (Gord. and Gland-..) Hoopes;
and c·aliforn:ia red fir, Abies magnifica A. Murr.
y
Hallin, William E.. 1951. Unit area control in California forests-'
California Forest and Range Experiment Station. Forest Research Note N'o• 77.
8 P• Berkeley, Calif.
\
rOR..ESTRY Ll!J..f?.AR_X
* MAINTAINED AT BERKELEY, CALIFORNIA, IN
Agriculture--Berkeley
COOPERATION WITH THE UNIVERSITY OF CALIFORNIA.
Study Area and Objectives
The timber stands of the study area, situated about 30 miles east
of Sonora,-are typical of th~ high site-quality sugar pine-fir type of
the western slopes of the Sierra Nevada. Elevation of the study area is
from 6,000 to 6,500 feet, near the ~pper elevational limit of sugar pine
in central·california. The terrain is characterized by gentle to steep
slopes, scattered benches, small feeder streams, and rocky ridges. Except
for the tops and upper slopes of .rocky ridges, all the land is Site A-200 ,
or Site I-175 (Region 5, Forest Service, site classes based on the heightage relation of dominant trees).
The merchantable volume (stand over 11.6 inches d.b.h.) was approximately 44 percent sugar pine, 39 percent white and red fir, 13 percent
California· incense-cedar (Libocedrus decurrens Endl.), and 4 percent
Jeffrey pine (Pinus jeffreyi Grev. and Balf.). The main brush species
present were manzanita (Arctostaphylos patula Greene), whitethorn or snowbrush (Ceanothus cordulatus Kell.), deerbrush (Ceanothus integerrimus
Hack and Am.), and chinquapin (Castanopsis sempervirens Dudley).
Of the 200 acres logged, 58 acres or approximately 30 percent,
were treated as regeneration areas. These unit areas, where silvicultural
treatments were aimed at securing sugar pine reproduction, varied in size
from one-fifth to 3 acres. Some were clear-cut with seed trees left
around the border for natural reproduction. The others were clear-cut
for g~eding and planting. The cut on these unit areas was 88,000 board
_fee~ per acre, resulting in large accumulations of slash.
Slash disposal and site preparation were done on the regeneration areas.
.
On the unit areas cut by other methods (group release and improvement) the original stand was 75,000 board feet per acre, of which 29,000
feet were cut. The resultant slash was not too great a fire hazard
because the bare regeneration areas and skid trails served as effective
firebreaks. Consequently the slash was not piledo
The objectives of slash disposal and site preparation were
threefold:
1. To clear logging debris, brush, and unwanted trees from
regeneration areas to facilitate seeding and planting.
2. To disturb .the ground and expose mineral soil, thus providing
a seedbed for sugar pine.
3.
To reduce the .fire hazard due to large accumulations of slash.
~Stand above 11.6 inches d.b.h. gross volume Scribner Decimal C
Log Rule.
-2-
After the logs were yarded from a regeneration area, the.... ~ash was
piled and the mineral soil exposed in one operatic~. Plot data2f indicate
that given an even start sugar pine can compete successfully with both
fir and brush. But if establishment of the pine is delayed, brush will
invade the ground cleared by cutting and will prevent subsequent establishment of pine unless costly erad.ication of brush is carried out. Eradicati:q.g well-established, vigorously growing brush is much more difficult than
eradicating the less-vigorous brtish occupying only part of the area immediately after logging. Thus the timing of this operation was important.
The site had to be prepared by September on areas that were to be regenerated naturally after seedfall. On ~rtifioial-regeneration areas the
site had to be readied and planted as soon after logging as possible so
that brush or inferior tree species would not take control of the area.
Also, to reduce the fire hazard and to put all the land back into a
productive state, the slash piles had to be burned as soon as possible.
Equipment and Technique
In 1948, two tractors, one of 80 hp. and one of 130 hp., with
cable-controlled angledozer blades were used at different times to pile
slash. in 1949 only the 80 hp. tractor was used. A 43 hp. tractor was
tried, using a cable-controlled angledozer equipped with brush-piling
teeth designed by Region 6, u. s. Forest Service. These teeth were
constructed so the dozer blade could be floated, that is, freed from
cable support, part of the time a load was being pushedo Thus most of
the disturbed soil oould pass between the teeth and not be picked up in
the load of slash. In practice, however, many root crowns of brush and
saplings also passed between the teeth, so the brush eradication was not
as effective as desired. Also, the 43 hp. tractor proved too small and
unstable for the task, and it was soon abandoned in favor of the 80 hp.
tractor.
The most satisfactory working team consisted of a job supervisor,
a oat skinner, and swamper. The supervisor examined regeneration areas
before work began on them and organized the work plan by:
1. Establishing the best boundaries of the area to be cleared for
regeneration;
2•
Establishing locations for piles or windrows of slash; and
3. Marking good patches of sugar pine seedlings or saplings that
were to be saved. Instructions were givento the oat skinner and swamper
in considerable detail. After the crew was trained the supervisor spent
. ·only an average of 2 hours a day laying out the areas and inspecting them
as clearing was complete~.
2/ Fowells,
H. A. 1944. Site preparation as an aid to sugar pine
regeneration. California Forest and Range Exp~riment Station. Forest
Research Note No. 41. 5 P• Berkeley, Calif.
-3-
ore·
pat
and
ole
do
ope
to
wer
194
end
fee
rei
cul
ble
eVE
yeE
ha:
thc
enc
lil
tht
th·
su
se
On
pi
so
AI
bi
ii
bl:
ar
ef
wj
p1
bt
F
B
;.
/
;e
;-
,.
The cat skinner and swamper were normally part of the yarding
crew in 1949. Their yarding assignment was to ground-skid logs from
patches of :eproduction and bunch the logs i~ openings so th~t a_tractor
and arch un~t would not have to be operated ~n the reproduct~on.11 T.he
clearing operation was balanced with the yarding work so one crew could
do both jobs satisfactorily. Using a two-man crew for the clearing
operation alone, as was done in 1948, proved inefficient for this 55,oooto 60 1 000-board feet per day logging operation.
Clearing Was begun as soon as a few adjoining regeneration areas
were logged, and was completed before the time of seedfall in 1948. In
1949·the sugar pine seed crop failed, so cle~ring was completed by the
end of the logging season to make the area ready for seeding and planting.
Besides the slash created by an average cut of 88,000 board
.
feet per acre, the cull logs, windfalls, high brush, litter, and scattered
reproduction were moved into the piles in 1948. Chokers were set on some
cull logs and other material to help move them to the piles. The dozer
blade was run over the regeneration area so that the mineral soil was
everywhere exposed as a seedbed.
Since the sugar pine seed crop failed in 1949, the clearing that
year was designed merely to facilitate planting and to reduce the fire
hazard. Some large windfalls and cull logs were left unpiled. Moving
them required much time and power, and it was obvious that most sizes
encountered would not interfere with the 6- by 6-foot spacing of seedlings. No special attempt was made to expose the mineral soil; yet in
the process of rooting out brush and piling slash, the bulldozer exposed
the soil on nearly all of the area. As a result the site was considered
sufficiently prepared to act as a seedbed for natural regeneration the
second year, too.
Slash piles were located on stump concentrations whenever possible.
On some of the larger regeneration areas having steep slopes, slash was
piled in windrows along contours. Some unburned slash and a terrace of
soil remained in the windrows after the burn and served to check erosion.
All slash piles and windrows were located so as to eliminate the possibility of scorching reserve timber when the slash was burned. All piles
in the cleared area were kept as compact as possible so that they would
burn clean and occupy a minimum of ground space. Experience with piling
and burning in 1948 indicated that the tractor operator should make an
effort to keep as much dirt as possible out of the piles. Soil mixed
with organic material creates pool" burning conditions and may cause some
piles to smoulder longer than is desirable. Pushing slash uphill should
be avoided as much as possible.
'!./
Cosens, Richard D. 1952. Reducing logging damage. California
Forest and Range Experiment Station. Forest Research Note No. 82.
Berkeley, Calif.
I
I
< I
~------
~--------
--
-----..--,---~-
--
-
--
~---------
----
-----
II!l
'•
I'
il'I
lr
!I
!!
i:
l
I
.,
'.. ~
Small groups of sugar pine seedlings and saplings were occasionally found in regeneration areas before clearing. When the trees had a
spacing of approximately 6 by 6 feet or closer (roughly 1000 per acre),
they were saved. Other species were out if present, the trash was thrown
out of the sugar pine group, and the tractor was kept out. On the other
hand, no special att~mpt was made to save scattered young trees not
meeting the spacing requirement.
As the object of clearing was to get sugar pine established,
seedlings, saplings, and scattered poles of other species, and high
brush were eliminated from the regeneration areas. For various reasons
it was sometimes diffioul t f.or the dozer blade to push these plants out
without also scooping up a large quantity of soil. The plants were left,
and the swamper out them with an axe. (A ~pound single-bitted axe was
best for this job.} He also out off some saplings knocked flat by the
logging operations and other small trees and brush that resisted the
dozer blade. Cleaning up the small trash on edges of piles and windrows
was best done by hand and with the aid of a pitchfork.
'' '
To reduce fire hazards, all men engaged in the clearing operation
coordinated their work so that no stringers of trash were left lying
between slash piles and the reserve timber. This eliminated the danger
of fire creeping to the live stands during the burning. Snag falling
was done after clearing was completed. The fallers out a firebreak
section out of any snag that extended from a slash pile into the reserve
timber. On his last inspection before the burning, the job supervisor
carried a shovel to clear up any shattered wood from snags or other
trashy fuel near slash piles.
r-
,c
Burning had to wait until the woods were wet because many large
piles of slash had been·' accumulated. Most piles burned very hot for a
few hours, and some carried a moderate amount of heat for several days;
some piles smouldered over winter. An occasional inspection of the
b~rning area was made during May, June, and July of the following season.
«
+=
+=0:
c
c:
I
Q
.,.I=
e-
Costs
Records of time and costs were kept for the slaah disposal and
site preparation phases of the job for both 1948 a~d 1949 (table 1}.
The lower oost.in 1949, i37.38 per acre cleared, cont~sted with 458.55
per aore.oleared in 1948, is largely the result of increased experience.
A better clearing blade for the tractor and more ~xperience in this type
of work should reduce the cost even more. The cos~ of slash disposal
and site preparation is presented in table 1 in three ways; (1) Per acre
of regeneration area, (2) per acre of gross area logged during season,
and (3) per thousand board feet, net landing scale, all timber out. An
operator's costs may be calculated from the man-day and hour-meter data
given.
-5-
,..
,!.
(
E
(!)
(!)
.
ai
~
•
..
in cf
ol
jj.
'i
~
,/
.....
~-.....
Table 1.- Time-cost tsble for slash disposal and site preparation
.
.
.
:
Item
: 1948
.:.
1949
Man days
Total
I
0)
I
60
..
:
1948
:
1949
Dollars
.
.:
Equipment
.
:
:
:
:
1948
:
1949
:
1948
:
:
1949
Total labor and
equiEent cost
..
Dollars
Hours
:
:
1948
1949
Dollars
$824.15
$622.68
155
62
$1049.45
$349.10
$1873.60
$971.78
1.67.
25.75
23.45
4.84
2.38
32.80
13.43
58.55
37.38
9.16
5.66
1.72
.56
11.66
3.17
20.82
8.83
43.5
Per acre of
regeneration area
1.88
Per acre,
gross area logged
.67
.40
Per M b.f.
all timber cut
.017
.010
Notes: 1.
:
:
Labor
.232
.141
~044
.014
.295
.079
.526
.220
Equipment use rates based on hour-meter readings: 43hp. tractor - $2.75; 80 hp. tractor - $6.55;
130 hp. tractor - $7.45. Rates include charges for operation (:fuel, grease, etc.)~ repairs, and
depreciation. Hours of use: 1948--80 hp. tractor, 117; 130 hp. tractor, 36. 1949--43:}lp. tractor,
15; 80 hp. tractor, 47.
·
2.
Acres out: regeneration--5-2 acres in 1948, 26 acres in 1949; gross--90 acres in 1948, 110 acres
in 1949.
3.
Net volume cut, Scribnerz 1948, 3,559,140 board feet; 1949, 4,413,460 board feet.
4.
Labor ·Costs consist of straight wages for an 8-hour day; no allowances for leave and holiday
pay. Labor of supervisory personnel .included. Average wage for an 8-hour day: 1948, $13.74;
1949, $14.31.
~
-
-~--~
--- -
p--~-~---
-
-
-
~
Discussion
It is obvious that possibilities for clearing slash from regeneration areas have been only briefly investigated. New machines, tools, and
methods Should be tried. There are now on the market various types of
land-clearing blades for attachment to tractors, most of them being
arrangements of different kinds of teeth. Tests may show some of these
blades to be satisfactory. If they all prove inadequate for the job,
good ones should be designed. The ideal clearing blade should cut off
live brush and small trees below ground level and move. the· slash to
piles Without picking up soil.
Whether or not the methods tried in slaSh disposal will result
in site deterioration is a question which Should be investigated. It
must be remembered that a bare mineral soil is considered to be essential
for establishing sugar pine reproduction by means of natural seedfall.
To date the effect of burned slash piles on restog~ng has not
been thoroughly investi::;ated. The information availabl~ shows no
significant difference in survival of seedlings between areas where slaSh
piles were burned and adjacent areas of bare soil.
In some localities it might be possible tQ sell limbs and chunks
for firewood or other uses, either before or after slash is piled. Large
accumulations of such material in regeneration areas, which are fairly
accessible over skid trails, might make the recovery of firewood, shake,
or post material an attractive enterprise for local residents.
! ;
Complete elimination of sprouting bruSh species does not result
from the slash disposal methods described here. Some species, li~e
whitethorn and chinquapin, sprout quickly. In an effort to control the
sprouts as they appear, . techniques of chemical spraying are being tested.
But complete elimination of brush may not be necessary since slash
disposal and site preparation are done only to give pine reproduction the
initial competitive advantage it needs to keep ahead of brush growth.
Present experience indicates that the preparation of regeneration
areas to receive seed or planting stock can be done at a reasonable cost,
and at the same time provide fireproofing measures for the logging area.
~Fowells, H. A., and G. H. Schubert. 1951. Recent di~ect
seeding trials in the pine region of California. California Forest and
Range Experiment Station. Forest Research Note No. 78. 9 P• Berkeley,
Calif.
-7-